Comparison of epidural and intramuscular pethidine for analgesia in labour.

Analgesia mediated by a direct spinal action of narcotic drugs administered via the epidural route may have considerable advantages over conventional(conduction block) epidural analgesia in labour. The efficacy, mode of action and placental transfer of epidurally administered narcotics in labour has not yet been established. We have compared the systemic absorption, analgesia and other effects on the mothers and transfer of drug to the fetus in primigravidae who received epidural or intramuscular pethidine 100 mg in labour. The superior analgesia following epidural pethidine did not appear to be attributable to a selective spinal action but rather to higher plasma concentrations of pethidine together with a possible weak regional conduction block due to local anaesthetic action of 1% pethidine solution. Epidural pethidine is not an advantageous method for providing analgesia in labour.